Advances in the development and improvements of the luminous flux of light-emitting devices such as semiconductor, organic or polymer light-emitting diodes (LEDs) have made these devices suitable for use in general illumination applications, including architectural, entertainment, and roadway lighting, for example. As such, LEDs are becoming increasingly competitive with light sources such as incandescent, fluorescent, and high-intensity discharge lamps.
Light-emitting diodes offer a number of advantages and are generally chosen for their ruggedness, long lifetime, high efficiency, low voltage requirements, and above all the possibility to control the color and intensity of the emitted light independently. They provide a great improvement over sensitive gas discharge lamps, incandescent bulbs, and fluorescent based lighting systems. Solid-state lighting sources have the capability to create similar lighting impressions but outweigh a number of drawbacks associated with other lighting technologies.
Many times it is required to create certain desired lighting effects such as homogeneous planar lighting impressions. To meet such requirements apparatuses were conceived that utilize modular elements in which the components can be easily placed, shaped, mounted, or maintained. Despite ongoing improvements in components and apparatus design, requirements for different shapes and forms still necessitate the assembly of tailor made components that entail a number of economic limitations. From a practical standpoint, any type of multipurpose lighting technology that allows for the building of a wide variety of solutions with a select few simple generic modular elements would be desirable.
A number of prior art references disclose the use of light-emitting devices in panel illumination or display apparatus. For example, U.S. Pat. Nos. 6,712,486, 6,683,665, 6,314,669 and 6,244,727 describe modular panel grid and array type lighting systems, which incorporate LEDs as the illumination source.
U.S. Pat. No. 6,058,634 discloses a LED lighting apparatus in a flat panel format used for illuminating customized light-emitting artwork. The lighting apparatus comprises a number of “tri-color” LEDs which are attached to a multi-layer printed circuit board (PCB). In order to mount the LEDs, the attachment and assembly process can only be done in a series of cutting, coating, and mounting steps which typically involve soldering. In addition, because of the employed tri-color LEDs and the color mixing control, the emitted light is limited to a range of orange colors including a pure saturated green and a pure saturated red.
Similarly, U.S. Pat. No. 6,232,724 discloses a “light emitting diode array” with a special-purpose designed signal interconnection board to which a number of LEDs are permanently mounted. The interconnection boards cannot be extended to create a homogeneous lit surface without leaving a substantial gap in between the LEDs, and can only be extended by means of a particular wiring system.
International Patent Application No. WO01/59747 discloses “light bodies for advertisements, displays and similar visible surfaces” which comprise a panel type assembly of serially connected LEDs on a modular PCB. The PCBs are pre-grooved such that custom sized large area LED modules can be easily truncated however the modules cannot be assembled to form a larger homogeneously lit surface without any additional optics. Individual modules can only be mounted to a detached base inside a special-purpose housing.
In addition, Silicon Bandwidth Inc. discloses a printed circuit board design with plated through holes and back drilled holes for use in high-density high-speed electrical signal interconnections. A technology white paper can be found at http://www.siliconbandwidth.com/prod_welltech.htm. The multi-layer board can be equipped with cylindrical holes to receive precisely manufactured variable length connector pins of packaged devices. However, only issues of electrical connectivity but no mechanical or thermal contact management are addressed and devices can only be placed at predetermined locations.
While there are many lighting systems that can achieve a homogeneously lit surface impression, the design of these systems is either monolithic or involves a number of custom made components that can require elaborate assembly procedures. In order to facilitate the design of customized lighting solutions and to simplify the assembly process, standardized modules need to be employed to substitute the function of otherwise custom-made components. Therefore there is a need for a new panel lighting system that enables the use of modular, rugged and easy to handle components.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.